“…The integrable systems by Kovalevskaya [1], Kovalevskaya-Yahya [11], Kovalevskaya on the Lie algebra (4) [12], Goryachev-Chaplygin-Sretensky [5], Sokolov [13], Dullin-Matveev [14] with the integrals of degrees 3 and 4 are modeled (that is, are piecewise smooth Liouville equivalent) in the suitable energy zones (that is, on the suitable constantenergy 3-manifolds) by the integrable topological billiards with the canonical integral of degree 2. In other words, the integrals of higher degrees are reduced to the one and the same quadratic integral…”